In recent years, there have been great advancements in the speed, power, and complexity of integrated circuits, such as application specific integrated circuit (ASIC) chips, random access memory (RAM) chips, microprocessor (uP) chips, and the like. These advancements have made possible the development of system-on-a-chip (SOC) devices. A SOC device integrates into a single chip all (or nearly all) of the components of a complex electronic system, such as a wireless receiver (i.e., cell phone, a television receiver, and the like). SOC devices greatly reduce the size, cost, and power consumption of the overall system.
Minimizing the power consumption of a processing system is becoming particularly important to consumers. Many popular electronic devices are portable systems that operate on battery power. Since maximizing battery life is a critical design objective in a portable device, it is essential to minimize the power consumption of the electronic device. Furthermore, even if an electronic device is not a portable system, minimizing power consumption is still an important objective. The increased use of a wide variety of electronic products by consumers and businesses has caused corresponding increases in the electric utility bills of homeowners and business operators. The increased use of electronic products also is a major contributor to the increased electrical demand that has caused highly publicized power shortages in the United States, particularly California.
Many popular business and consumer electronic products are capable of communicating via an external network, such as the Internet. Typically, these products use a network interface card (NIC) to connect to and communicate over the external network. An Ethernet NIC is one of the most common network interface cards and is used to communicate via the Internet. An Ethernet NIC may be used in portable processing systems, such as laptop personal computers, and stationary processing systems, such as desktop computers, servers, Internet phones, copy machines, printers, and the like.
Each processing system that hosts a network interface card (NIC) must supply the application specific integrated circuit (ASIC) chip in the NIC with multiple supply voltages that power the ASIC chip. However, a processing system that is capable of communicating over an external network does not always use the external network, even when it is connected to the external network. In order to avoid wasting power, it is desirable to minimize the power drain of a NIC when the external network is not being used. This is especially true for battery-powered processing systems, such as laptop computers, since the power drain of the NIC shortens battery life.
There are a number of detection schemes that automatically power down the ASIC chip(s) in a NIC when it appears that no data traffic is active on the external network connection. These schemes are generally referred to as “wake on LAN” and are implemented by many Ethernet NIC manufactures. However, a small, but significant, power drain still occurs in the ASIC chip(s) of the NIC. Monitoring circuits that keep the NIC circuitry minimally active in case the network suddenly becomes active or the user re-enables the telecommunication abilities of the NIC cause this power drain. It is preferable to completely eliminate this power drain when the processing system and NIC are not coupled to an external network at all.
Therefore, there is a need in the art for improved apparatuses for reducing power consumption in network-capable processing systems. In particular, there is a need for an apparatus that completely shuts off power to the components of a NIC when the NIC is not connected to an external network.